Power transmission



June 23, 1970 L, PERKMS 3,516,767

POWER TRANSMISSION 2 Filed Nov. 14, 1968 28 l8 Q lllHHl llllllll I] ll] lllll' lll'lIHH FIG. 3'

INVENTOR. EDGAR L. PERKINS ATTORNEYS BY a United States Patent O 3,516,767 POWER TRANSMISSION Edgar L. Perkins, Detroit, Mich., assignor to Sperry Rand Corporation, Troy, Mich., a corporation of Delaware Filed Nov. 14, 1968, Ser. No. 775,850 Int. Cl. F04c 1/00, 3/00, 17

US. Cl. 41881 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to power transmissions and is particularly applicable to those of the type comprising two or more fluid pressure energy translating devices, one of which can function as a pump and the other as a fluid motor. More particularly, this invention relates to an improvement in sliding vane type pumps and motors.

Units of this type generally comprise a stator including a vane cam track within which is rotatably mounted a rotor carrying radially sliding vanes to form fluid inlet and fluid outlet working zones located between the periphery. of the rotor and the vane track, either of which may be a low pressure or a high pressure Working zone dependent upon the pump or motor function of the device. In such devices, the rotor is encased between a pair of cheek plates which provide a means for directing 'fluid pressure to and from pressure working zones. A certain predetermined clearance is allowed between therotor and each cheek plate for the purpose of connecting the fluid working zones to the drive shaft upon which the rotor is mounted; thus, not only is fluid provided for lubricating the drive shaft, but a fluid 'film is created between the rotor and each cheek plate for preventing rotor-cheek plate contact.

At high speed and pressure operation, there is a notable pressure drop across the face of therotor which, in addition to other forces acting'on the rotor, causes the rotor to shift towards one of the cheek plates, causing contact between the two with a resultant excessive wear between the rotor and the cheek plates that causes noisy and ineflicient operation, and a shortening in the life of the device.

This predetermined clearance between the rotor and the cheek plates is' designed such that the leakage thereacross will be sutficientto provide an acceptable fluid film for lubricating purposes, but without significantly impairing the volumetric efliciency of the device. If a rotor, which is initially centered between the two cheek plates, shifts so as to come into contact with one of the cheek plates, the leakage path between the opposite rotor face and cheek platewill be twice as great; and since the leakage rate will vary by the cube of the distance between the rotor and plate, the rate of leakage between the opposite rotor face and cheek plate will be approximately eight times greater than when the rotor was centrally positioned between the two plates with the net elfect that system leakage is substantially increased.

It would thus be very desirable to provide a fluid device of the type described in which the rotor is centrally lo- 3,516,767. Patented June 23, 1970 cated between the two cheek plates during all phases of operation.

SUMMARY OF THE INVENTION This invention comprises a rotary fluid pressure energy translating device of the sliding vane type having a rotor rotatably mounted between two cheek plates and a pair of pressure pools located on each plate and facing the rotor; including means forming a fixed restriction connecting the pool to a source of high pressure energy, and means forming a variable restriction exhausting the pool; the size of the variable restriction being dependent upon the distance between the rotor and cheek plates.

It is therefore an object of this invention to provide an improved, eflicient, and long wearing fluid pressure energy translating device of the sliding vane type.

It is also an object of this invention to provide such a device having an improved rotor-cheek plate construction which reduces noise and wear between the same.

It is a further object of this invention to provide such a device which is capable of both high pressure and high speed operation without an excessive amount of leakage between the rotor and the associated cheek plates.

It is still another object of this invention to provide such a device having all the advantages previously recited without substantially increasing the overall dimensions or cost of devices currently in production.

It is still another object of this invention to provide a device of the type described having all the hereinbefore advantages by incorporating an all-hydraulic, non-mechanical rotor centering means.

Further objects and advantages of the present invention will be apparent from the following description, reference being made to the accompanying drawing wherein a preferred form of the invention is clearly shown.

IN THE DRAWING DESCRIPTION PREFERRED EMBODIMENT Referring now to the several figures, there is shown a presently preferred, but merely illustrative embodiment of the inventive principles: a pump 10 of the sliding vane type. The housing 12 of the pump 10 comprises a cam ring section 14 sandwiched between the body section 16 having a wear plate 18 and an end cover 20 all of which are suitably connected to each other by bolts 22. The body section 16 is provided with an inlet supply connection port 21 having an inlet passage 24 leading therefrom and which is branched and terminates in a pair of fluid openings, one of which is shown in FIG. 1 and indicated by the numerical 25. The branched passageways register with duplicate opposed fluid openings 26 and 27 extending through the wear plate 18 and which are shown in FIG. 3 as dotted lines.

The body section 20 is provided with an outlet connection port 28 having an outlet passage 30 leading therefrom which has two branches 32 and 34, as shown in FIG. 1. Branched passageways 32 and 34 respectively terminate in a pair of diammetrically opposed arcuately shaped fluid port openings 36 and 38, respectively, each of which are shown in FIG. 2. There is provided within the wear plate 18 diammetrically opposed arcuately shaped fluid port openings 40 and 42 (FIG. 3) which are opposite the end cover outlet ports 36 and 38 and are in fluid communication with each other in a manner to be described hereinafter. Within the end cover 20, there is provided another pair of diammetrically opposed arcuately shaped fluid openings 44 and 46 (FIG. 2) which are opposite the fluid inlet openings 26 and 27 within the body 16 and again are in fluid communication in a manner to be described hereinafter. The face of the end cover 20 in which the fluid port openings are formed will hereinafter be referred to as a cheek plate and will be indicated by the numeral 48 and the face of the wear plate 18 in which fluid port openings are formed will also be referred to as a check plate and will be indicated by the numeral 50.

A rotor 52 having an axial width which is slightly less than the axial width of the cam ring 14 is sandwiched between the two cheek plates 48 and 50 and is rotatably mounted within the cam section 14 on a splined portion 54 of a drive shaft 56 which, in turn, is rotatably mounted within bearings 58 and 60 mounted within the body section 16. A seal 62 is provided to prevent leakage passing the shaft 56 during operation. Seals 64 and 66 prevent leakage at the junction of the end cover 20 and the wean plate 16 with the cam ring 14 while seal 68 prevents leakage at the juncture of the body 16 and the wear plate 18. The seals 64, 66, and 68 are preferably in the form of an endless elastomeric O ring of circular radial cross section.

The inner surface of the cam ring 14 forms a cam track which is substantially elliptical in shape and indicated by the numeral 70 and against which the outer end of vanes 72 are adapted to be maintained in contact. The vanes 72 are movable in and out of slots 74 provided in the rotor 52 as the rotor turns around within the cam ring 14. The cam track contour and the outer periphery of the rotor define two opposed working chambers indicated by the numerals 76 and 78, each of which, for the purpose of convenience, may be divided into a fluid inlet zone and a fluid delivery zone. The fluid inlet zones are those portions of the working chambers 76 and 78 registering with the opposed fluid inlet openings 26 and 27 in the cheek plate 50. The fluid delivery zones are those portions of the working chambers 76 and 78 registering respectively with opposed arcuate fluid delivery ports 36 and 38 in the cheek plate 48. Fluid communication between ports 36, 38, 42, and 40 is accomplished by means of their associated fluid zones while axial passageways 80 and 82 illustrated in FIG. 3 also connect the fluid inlet ports 26 and 28 with ports 44 and 46 in addition to the communication obtainable via their associated fluid zones.

Vane track 70 includes an inlet zone ramp extending from A to B (FIG. 3), a true are portion extending from B to C, a delivery zone ramp extending from C to D, and another true are portion extending from D to E. The track is symmetrical about both its major and minor axes; thus, each of the ramps and true are portions from A to E are duplicated in the opposite portion of the track. As the ends of thevanes traverse the inlet ramps, the vanes move radially outward with respect to the rotor, and While the vanes 72 traverse the delivery ramps, the vanes move radially inward. Within the true are portions, the vanes generally partake of no radial movement, however, a slight cant may exist in the true are portion to provide a proper compression and decompression of the fluid enter-' ing and leaving the ramp zones.

The inner ends of the vane slots 74 are enlarged to form with the inner ends of the vanes 72 closed undervane pressure chambers 84 to which fluid pressure is supplied for the purpose of maintaining the vanes against the cam track during a cycle of the device. Each cheek plate 48 and 50 has respectively annular feed grooves 86 and 88 formed therein. Fluid pressure is suppli to the groove 86 by means of axial passageways 90 and 92, one of which is clearly illustrated in FIG. 1. The annular groove 86 is in fluid communication with the undervane pressure chambers 84 and is adapted to supply fluid pressure thereto as the same rotates through a cycle of the device. Fluid pressure entering undervane chambers 84 is adapted to be transmitted to the annular groove 88 within the wear plate 18 for a purpose to be explained hereinafter.

Within the end cover 20 there is formed a recess 94 which, together with the spacing between the shaft and rotor splining at 54 and a spacing 96 between the wear plate and shaft, form a medium through which fluid is supplied from the inlet 27 via a slot 97 to lubricate the drive shaft and which may alternately be connected to a case drain, not shown, for the purpose of carrying off excess fluid.

There is provided in each cheek plate 48 and 50, respectively, grooves, or pressure pools 98 and 100 the purpose of which will be explained hereinafter. Between the pressure pools 98 and 100 and the recess 94 and spacing 96, respectively, there is provided annular sealing lands 102 and 104, the purpose of which is to cooperate with the opposite faces of rotor 52 to vary the amount of fluid flowing from the pressure pools 98 and 100 to the recess 94 and spacing 96, respectively. Fluid pressure is supplied to the pressure pool 98 by means of V-shaped grooves formed at strategic locations on land 103 within cheek plate 48 and which connect the pressure pools 98 to the annular shaped groove 86, and are indicated by the numerals 106 and 108. Within cheek plate 50 there is provided a similar pair of V-shaped grooves formed on land 107 for connecting pressure pool 100 to the annular shaped groove 88 and which are illustrated by the dotted lines shown in FIG. 3, indicated by the numerals 110 and 112. Thus, it can be seen that a continuous flow path is established between the high pressure port 28 and the recess 94 and spacing 96 by means of passageway 30, bores 90 and 92, the annular shaped groove 86 and via pressure groove 84 and the annular shaped groove 88, through the V-shaped grooves 106, 108, 110 and 112, into the pressure pools 98 and 100 and across the sealing lands 102 and 104. It should be noted that although two V-shaped grooves are illustrated on each cheek plate in the several figures, one such V-shaped groove may be utilized on each cheek plate. I

Since the depth of the V-shaped grooves is relatively large as compared to the clearance between the cheek plate and the rotor, the V-shaped notches may be considered as fixed flow restrictions; whereas, the flow across the sealing pads will be varied with respect to the distance between the rotor and its associated cheek plates.

Referring momentarily to the cheek plate 48 and the associated face of the rotor for an explanation of the operation of the pressure pools, it can be seen that the pressure in pool 98 will be dependent upon the annular clearance between the sealing pad 102 and the face of the rotor. Since the V-shaped groove is considered a fixed restriction, the flow from the annular groove 86 to the pressure pool may be considered as a constant. If the rotor 52 moves close to the surface of cheek plate 48, the variable restriction across the sealing land 102 will decrease, thus causing the pressure in pressure pool 98 to rise. The force generated against the rotor 52 by means of the pressure in pool 98 is a function of the pressure in the annular area of pool 98. Since the pressure is rising, the force exerted against the rotor tending to shift the same rightwardly, as viewed in FIG. 1, will increase.

Referring now to the opposite side of rotor 52 and the pressure pool 100, its operation is identical to the pressure pool 98. When the rotor is shifted leftwardly towards the pressure pool 98, the area between the sealing land 104 and the face of the rotor increases with the resultant efifect that the pressure in pressure pool 100 decreases,

since the flow across the sealing land has been increased substantially.

Considering, now, both pressure pools, and their resultant effect on the rotor, the pressure in pressure pool 98 has increased because of the leftwardly shift of the rotor while the pressure in pressure pool 100 has decreased. Thus, it can be seen that the resultant hydraulic forces acting on the rotor is such that the rotor will be shifted rightwardly since the areas of the two pressure pools are equal and the pressure in pressure pool 98 will greatly exceed the pressure in pool 100.

As a rotor tends to shift rightwardly towards the pressure pool 100, the pressure in that pool will tend to rise in the same manner as described hereinbefore with respect to the pressure pool 98. In this case, the pressure in pool 98 will tend to decrease and again the net result of the hydraulic forces acting on rotor 52 will be to shift the same leftwardly away from the pressure pool 100. It can thus be seen that whenever the rotor shifts towards one of the cheek plates, the pressure build-up in the pressure pool associated with that plate will be such as to oppose this movement with the net effect that the rotor will tend to be centered between the two cheek plates. When the rotor is centered, the effective area across each of the sealing lands will be the same, with the pressure in each of the pressure pads being equal, and thus, the rotor will tend to remain in a stable position with the clearance between the rotor and the cheek plate being approximately equal on opposite sides thereof.

It can thus be seen that the present invention provides a fluid pressure energy translating device of the sliding vane type having an improved rotor cheek plate construction in which the rotor is centered between the cheek plate by non-mechanical, hydraulic means with the net result that noise and wear between the cheek plates and associated faces of the rotor are reduced to a minimum. It can further be seen that the present invention has provided such a device in which leakage between the rotor and associated cheek plates is kept to a minimum, thus providing a unit with an improved volumetric efiiciency.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow:

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A fluid pressure energy translating device comprising: a housing having low and high pressure operating passages, one of which is an inlet passage and the other an outlet passage; a cam track in said housing; a pumping mechanism rotatably mounted within said cam track forming fluid inlet and fluid outlet zones between the outer periphery of said pumping mechanism and said cam track; means forming a pair of cheek plates on opposite sides of said pumping mechanism, said check plates being disposed for relative rotary movement with said pumping mechanism and defining between said pumping mechanism and each of said cheek plates a leakage path originating from said fluid zones, said pumping mechanism being responsive to force exerted thereon to shift the same towards one of said check plates thereby decreasing the size of one of said leakage paths; means forming a pressure pool disposed between each of said cheek plates and said pumping mechanism wherein the fluid pressure in each of said pools creates a force exerted on said rotor to shift the same away from said cheek plates; means forming a plurality of restrictions for separately connecting each of said pools to said high pressure operating passage; means forming a plurality of variable restrictions for separately exhausting fluid pressure from each of said pools whereby the pressure in said pools and thereby the force exerted on said pumping mechanism is increased in response to decreases in the size of said variable restrictions and vice versa.

2. A combination as in claim 1 including means for varying said variable restrictions in response to the distance between said pumping mechanism and said check plates such that the size of the variable restriction associated with the cheek plate in which said rotor is being shifted towards will decrease while the size of the variable restriction associated with the other cheek plate is increasing whereby said pumping mechanism tends to be centrally positioned between said cheek plates for maintaining said leakage paths on opposite sides of said pumping mechanism.

3. A combination as in claim 1 wherein said pressure pool means comprises an annular shaped recess formed on each cheek plate opposite said pumping mechanism.

4. A combination as defined in claim 1 including a low pressure area to which said leakage paths on opposite sides of said pumping mechanism connect said fluid zones; and an annular sealing land disposed between said pumping mechanism and each of said cheek plates within said leakage paths between said pressure pool means and said low pressure area wherein said variable restriction means associated with each pressure pool comprises the annular distance between the pumping mechanism and annular sealing land associated therewith.

5. A combination as in claim 4 wherein said pressure pool means comprises an annular recess formed on each cheek plate opposite said pumping mechanism.

6. A combination as in claim 5 wherein said sealing lands are formed on each cheek plate opposite said pumping mechanism.

7. A combination as in claim 2 wherein said pressure pool means comprises an annular shaped recess formed on each cheek plate opposite said pumping mechanism.

8. A combination as defined in claim 2 including a low pressure area to which said leakage paths on opposite sides of said pumping mechanism connect said fluid zones; and an annular sealing land disposed between said pumping mechanism and each of said cheek plates within said leakage paths between said pressure pool means and said low pressure area wherein said variable restriction means associated with each pressure pool comprises the annular distance between the pumping mechanism and annular sealing land associated therewith.

9. A combination as in claim 8 wherein said pressure p001 means comprises an annular recess formed on each cheek plate opposite said pumping mechanism.

10. A combination as in claim 9 wherein said sealing lands are formed on each cheek plate opposite said pumping mechanism.

References Cited UNITED STATES PATENTS 2,919,651 1/1960 Gardiner 103-136 3,447,477 6/1969 Pettibone 103-136 3,455,245 7/1969 Reichling 103-136 X DONLEY J. STOCKING, Primary Examiner W. J. KRAUSS, Assistant Examiner U.S. Cl. X.R. 418- 

